Fast Growth of Immature Brood in a Social Parasite Wasp: A Convergent Evolution between Avian and Insect Cuckoos.

Studies on avian cuckoos have demonstrated that parasite chicks compete with host fledglings to monopolize food or manipulate the foster parents to increase their provisioning rate. This topic has never been explicitly investigated in insect social parasites, which use the social system of another species to raise their brood. Here we show that the immature brood of the cuckoo wasp Polistes sulcifer grows more rapidly than the host immature brood. Host workers perform more parental care to parasite larvae than to conspecific ones. Thus, the rapid growth of the parasite larvae is evidently due to increased host care, which prolongs the development of host larvae reared in the same colony. We suggest that parasite larvae play an active role in host exploitation through manipulation of host workers, as occurs in parasitic birds.